I. Oxidation reaction

Most alkanes will undergo oxidation reactions, but require activation energy, such as a spark in the following reaction.

Eg. Methane + Oxygen

CH4

+

2O2

CO2

+

2H2O

Methane

+

Oxygen

Carbon dioxide

+

Water

 

II. Reduction reaction

CO2

+

3H2

CH3OH

+

H2O

Carbon dioxide

+

Hydrogen

Methanol

+

Water

 

 

III. Halogenation (by substitution reaction)

Alkanes will react with halogens at high temperatures, or in light to yield several products demonstrating substitution of one or more of the hydrogen atoms.

CH4	+	Cl2			CH3Cl	+	HCl
Methane	+	Chlorine			Chloromethane	+	Hydrochloric acid
CH3Cl	+	Cl2			CH2Cl2	+	HCl
Chloromethane	+	Chlorine			Dichloromethane	+	Hydrochloric acid
CH2Cl2	+	Cl2			CHCl3	+	HCl
Dichloromethane	+	Chlorine			Trichloromethane	+	Hydrochloric acid
CHCl3	+	Cl2			CCl4	+	HCl

Trichloromethane

+

Chlorine

Tetrachloromethane

+

Hydrochloric acid

 

 

 

IV. Dehydrogenation (by elimination reaction)

CH3CH2CH2CH3

CH3CH2CH=CH2

+

H2

Butane

1-Butene

+

Hydrogen

( Reaction in detail)

H

H

H

H

H

H

H

H

|

|

|

|

|

|

|

|

H-

C-

C-

C-

C-

H

H-

C-

C-

C

=

C

+

H2

|

|

|

|

|

|

|

H

H

H

H

H

H

H

 

 

 

V. Isomerization (by rearrangement reaction)

CH3CH2CH2CH3		CH3	CH	CH3
			|
			CH3
Butane		tert-butane

( Reaction in detail)

H

H

H

H

H

H

H

|

|

|

|

|

|

|

H-

C-

C-

C-

C-

H

H-

C-

C-

C-

H

|

|

|

|

|

|

|

H

H

H

H

H

H

H-

C-

H

|

H

 

 

 

 

VI. Intermolecular Dehydration

Sayteff's Rule: During intermolecular dehydration, if there is a choice of positions for the carbon-carbon double bond, the preferred location is the one that generally gives the more highly substituted alkene.

Note: Predicting the major product.

1. Remove the H and OH from adjacent carbon atoms to produce the double bond.

2. If there are choices as to which carbon atoms to use, remove the H from the carbon atom with the fewer H atoms attached

H

H

H

H

H

H

H

H

|

|

|

|

|

|

|

|

H-

C-

C-

C-

C-

H

H-

C-

C-

C

=

C-

H

+

HOH

|

|

|

|

|

|

H

H

OH

H

H

H

2-butanol

1-butene

water

minor product

H

H

H

H

|

|

|

|

H-

C-

C=

C-

C-

H

+

HOH

|

|

H

H

2-butene

major product

water

 

 

VII. Cracking

C18H38

C10H22

+

C8H16

Alkane

Alkane

+

Alkene